To switch off the attack, Marco Prinz at the University of Freiburg, Germany, and colleagues, took mice genetically modified to present symptoms of MS and injected them with RNA that stimulates the production of a protein called interferon-b (IFNb).

The mice showed “rapid improvement” with a decrease in tail weakness and paralysis over the following 48 hours. Increased IFNb appeared to slow the development of T-cells – immune cells that may play a key role in MS (Nature Neuroscience, DOI&colon; 10.1038/nn.2964).

Around 80 per cent of people with MS treated with injections of IFNb develop antibodies which reduce the efficacy of the protein. Getting the body to generate its own IFNb neatly dodges the antibody problem.